The complexity of present day machinery for a wide variety of applications has necessitated the use of a diversity of fastener and fitting sizes, for example, nuts and bolt heads of different sizes dictated by the mechanical design. Additionally, with the increasing use of metric size fasteners, some machines use both SAE and metric type fasteners, while others are limited to one of the fastener types. It is difficult to visually ascertain the size and the type of the fastener.
In the initial fabrication of such machines, and more particularly in the subsequent servicing thereof, as in the automotive field, the selection of sockets or wrenches of different sizes to accommodate the nuts and bolts becomes a time consuming, inefficient operation. Further, the fasteners are sometimes situated in areas having limited access.
What is desired is a tool which may be easily manipulated by one hand, leaving the other hand free to grasp the proper wrench or socket, and which tool, when applied to the nut or bolt, will give an accurate direct numerical reading of the SAE or metric size of the fastener. The gauge of the present invention provides such a tool.